It's worked great for me on an Easy2boot flash drive (which has a ton of other ISO images). I just had to drop the Sysrescue iso in the _ISO/Linux folder. The only time it didn't boot (or I ran out of patience) is booting on a Pentium 4, which was probably the fault of the BIOS USB speed and possibly fixed via firmware update. On that system, I used a burned ISO. But on newer systems, USB booting with Easy2boot is 10x faster than optical drives (even with USB 2.0).